I can provide a few examples.
The first isn't a personal lesson learned, but a very important message for newbies and the inexperienced: Do not believe everything that you read on this forum. I'm convinced that over half the forum members do not speak from personal experience. Instead, they recycle things that they've either read in some pick up book or heard on some youtube channel. Sometimes, these other sources are correct. Other times, they aren't even close. There could always be other variables at play (a woman's mood, her past, her upbringing, and of course, the impression we make upon them, etc..) In other words, it's better to think (based on your own experiences and observations) ... than to believe a bunch of group think.
----- Personal Mistakes that I've made------
Most of the below mistakes I made were decades ago (I'm one of the older forum members). It's my hope that by sharing my past blunders, that it may prevent some of you from making my previous mistakes. No matter our age, we will still make some mistakes. Our goal should be to learn and improve from each one. The fewer with each passing year, the better.
Asking a woman for advice about a female interest is always helpful and good. I was wrong.
Trust your gut and/or ask advice from someone you know that is successful with women. After observing female behavior, I leaned that their actions quite often will contradiction their words. Verdict: ."Actions speak louder than words." Always remember this-especially with women.
She can't help they way she is, give her plenty of concessions. I was wrong.
While I do believe that we should provide a little wiggle-room to men and women and try to practice some compassion and understanding, we shouldn't make excuses for patterns of bad female behavior. Usually, the truth is... we don't want to let go and making excuses for their bad behavior, helps to 'justify' our weakness (I've been there).
If things aren't going as good as they once were, change who you are and accommodate her needs. I was wrong.
Men are biologically wired to 'fix things.' Modifying and calibrating aren't always bad things, but be sure that you aren't compromising your individuality. Although women might say that they'd prefer it if we were more ____ (insert something they've read in some women's magazine etc...) they really do not know what they always want. Remember this! If you change the core of who you really are... you are also removing the very attributes that attracted her to you in the first place. Despite a lot of group-think on this forum, higher quality women gravitate more to the individual than to the conformist.